:Product: 1018RSGA.txt :Issued: 2010 Oct 18 2200 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Weather Prediction Center and the U.S. Air Force. # Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 291 Issued at 2200Z on 18 Oct 2010 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was at low levels. Region 1112 (S19W58) was responsible for all the periods activity which included a long duration C2.5 x-ray event at 18/1643Z. The region decayed slightly in area and spot count, but maintained a beta-gamma magnetic configuration. Region 1113 (N18E10) had several point brightenings observed during the period. IB. Solar Activity Forecast: Solar activity is expected to remain at predominately very low to low levels all three days of the forecast period (19 - 21 October), with a chance for M-class events from Region 1112. IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field was quiet at all latitudes. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels all three days of the forecast period (19 - 21 October), with isolated minor storm periods possible on 19 October. A coronal hole high speed stream (CH HSS) is expected to rotate into a geoeffective position late on 18 October or early on 19 October, followed by a second geoeffective CH HSS expected to arrive early on 20 October. These features, coupled with possible effects from the CME observed on 14 October, are the reasons for the forecasted increase in geomagnetic activity. III. Event Probabilities 19 Oct-21 Oct Class M 25/25/25 Class X 01/01/01 Proton 01/01/01 PCAF Green IV. Penticton 10.7 cm Flux Observed 18 Oct 091 Predicted 19 Oct-21 Oct 090/090/090 90 Day Mean 18 Oct 081 V. Geomagnetic A Indices Observed Afr/Ap 17 Oct 010/011 Estimated Afr/Ap 18 Oct 004/005 Predicted Afr/Ap 19 Oct-21 Oct 012/012-008/010-008/008 VI. Geomagnetic Activity Probabilities 19 Oct-21 Oct A. Middle Latitudes Active 30/20/20 Minor storm 15/05/05 Major-severe storm 01/01/01 B. High Latitudes Active 35/25/25 Minor storm 20/15/10 Major-severe storm 01/01/01